drm/v3d: Stop active perfmon if it is being destroyed

Commit 21f1435 upstream

If the active performance monitor (`v3d->active_perfmon`) is being
destroyed, stop it first. Currently, the active perfmon is not
stopped during destruction, leaving the `v3d->active_perfmon` pointer
stale. This can lead to undefined behavior and instability.

This patch ensures that the active perfmon is stopped before being
destroyed, aligning with the behavior introduced in commit
7d1fd36 ("drm/v3d: Stop the active perfmon before being destroyed").

Cc: stable@vger.kernel.org # v5.15+
Fixes: 26a4dc2 ("drm/v3d: Expose performance counters to userspace")
Signed-off-by: Christian Gmeiner <cgmeiner@igalia.com>
Signed-off-by: Maíra Canal <mcanal@igalia.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241118221948.1758130-1-christian.gmeiner@gmail.com

Author: Christian Gmeiner

drivers/gpu/drm/v3d/v3d_perfmon.c

@@ -384,6 +384,7 @@ int v3d_perfmon_destroy_ioctl(struct drm_device *dev, void *data,
 {
 	struct v3d_file_priv *v3d_priv = file_priv->driver_priv;
 	struct drm_v3d_perfmon_destroy *req = data;
+	struct v3d_dev *v3d = v3d_priv->v3d;
 	struct v3d_perfmon *perfmon;
 
 	mutex_lock(&v3d_priv->perfmon.lock);
@@ -393,6 +394,10 @@ int v3d_perfmon_destroy_ioctl(struct drm_device *dev, void *data,
 	if (!perfmon)
 		return -EINVAL;
 
+	/* If the active perfmon is being destroyed, stop it first */
+	if (perfmon == v3d->active_perfmon)
+		v3d_perfmon_stop(v3d, perfmon, false);
+
 	v3d_perfmon_put(perfmon);
 
 	return 0;